The present invention relates to a refrigeration cycle using a non-azeotropic refrigerant, and more particularly, to a refrigeration cycle suitable for a decrease in capacity and an increase in operation efficiency by changing the composition of a refrigerant circulating in the refrigeration cycle at low load.
Conventionally, in order to exhibit a capacity conformed to load, a compressor is inverter-driven to change the mass flow rate of a refrigerant circulating in a refrigeration cycle. Another system, in which a non-azeotropic refrigerant is used as a refrigerant and a distiller is used to change the composition of the refrigerant for production of a capacity suitable for load at all times, is known and disclosed in, for example, Japanese Patent Unexamined Publication No. 9-196481.
In the above-described prior art, the system adapted for capacity control through inverter-driving is difficult to operate at very low and very high speeds of compressor, so that it cannot but entail upper and lower limits in inverter frequency. Therefore, capacity control is effected by making the compressor on/off particularly at low load, thus leading to a poor efficiency. Also, with the system using a distiller, the distiller and a separation circuit thereof are large in scale to make it difficult for the system to be rendered compact in size.
An object of the present invention is to magnify capacity control for an increased efficiency and achievement of compactness. Another object of the present invention is to magnify the capacity on a side of low load to afford an energy-saving operation for a reduction in annual power consumption and adaptation to environment, such as prevention of destruction of ozone layer and an increase in recycle efficiency.
In order to solve the above problems, the present invention provides a refrigeration cycle composed of a compressor, a four-way valve, a heat exchanger on the heat source side, a liquid receiver, a heat exchanger on the use side, and an electronic expansion valve, which are connected by piping, the refrigeration cycle comprising a refrigerant being a non-azeotropic refrigerant to circulate therein, a second liquid receiver for taking out a refrigerant vapor from an upper portion of the liquid receiver to condense and store the refrigerant, and a pipe for connecting the second liquid receiver to the liquid receiver via a shut-off valve.
Thus, the use of a non-azeotropic refrigerant (for example, a HFC refrigerant mixture such as R407C having an ozone layer destruction coefficient of zero) results in that the refrigerant vapor in the liquid receiver contains much low boiling point refrigerant in composition and an amount of the refrigerant stored in the second liquid receiver and containing an abundant amount of low boiling point refrigerant can be changed by the opening and closing actions of the shut-off valve, so that the capacity of an air conditioner can be controlled by changing the composition ratio of a refrigerant circulating in the refrigeration cycle, and also a refrigerant rectifying column can be dispensed with which serves as separating components of the refrigerant mixture depending upon differences in boiling point among the respective component and which is liable to become large-sized, complicated, and expensive. Therefore, the number of on/off operations of an associated compressor can be decreased by increasing the capacity control range without hindering the compactness of an air conditioner, so that the air conditioner can be enhanced in efficiency and comfort.
Also, the present invention provides a refrigeration cycle having a compressor, a heat exchanger on a side of a heat source, an electronic expansion valve, and a heat exchanger on a side of use, and using a non-azeotropic refrigerant as a circulating refrigerant, the refrigeration cycle comprising a liquid receiver provided between the heat exchanger on the heat source side and the heat exchanger on the side of sue, and a second liquid receiver connected to an upper portion of the liquid receiver through a pipe, and wherein a refrigerant vapor, in which a low boiling point refrigerant is rich, is taken out from the liquid receiver, and the taken-out refrigerant is condensed and stored or returned to the refrigeration cycle, whereby the refrigerant circulating in the refrigeration cycle is changed in composition.
Further, in the above-described refrigeration cycle, the refrigerant vapor is preferably caused to make heat exchange with a refrigerant on a suction side of the compressor to thereby be condensed.
Further, in the above-described refrigeration cycle, the second liquid receiver is desirably connected to the suction side of the compressor via a second shut-off valve and a pressure reducing mechanism.
Further, the above-described refrigeration cycle desirably further comprises a heat exchanger for heat exchanging the refrigerant vapor with a refrigerant on the suction side of the compressor, a shut-off valve provided between the liquid receiver and the heat exchanger, and a pipe connecting the second liquid receiver to the suction side of the compressor via a pressure reducing mechanism.
Further, the above-described refrigeration cycle desirably further comprises a heat exchanger for heat exchanging the refrigerant vapor with a refrigerant on the suction side of the compressor, a shut-off valve provided between the liquid receiver and the heat exchanger, a pipe connecting the second liquid receiver to the suction side of the compressor via a pressure reducing mechanism, and a pipe connecting the liquid receiver to the second liquid receiver.
Further, the above-described refrigeration cycle desirably further comprises a heat exchanger for heat exchanging the refrigerant vapor with a refrigerant on the suction side of the compressor: and a check valve provided between the liquid receiver and the heat exchanger.
Further, the present invention provides a refrigeration cycle including an outdoor unit provided with a compressor and a heat exchanger on a side of a heat source, and a plurality of indoor units, and using a non-azeotropic refrigerant as a circulating refrigerant, the refrigeration cycle comprising a liquid receiver provided between the heat exchanger on the heat source side and the indoor units, and a second liquid receiver connected to the liquid receiver via a pipe, and wherein a refrigerant vapor, in which a low oiling point refrigerant is rich, is taken out from he liquid receiver and the taken-out refrigerant is condensed and stored, whereby the refrigeration cycle is operated with a high ratio of a high boiling point refrigerant contained in the refrigerant circulating in the refrigeration cycle.
Further, the present invention provides a refrigeration cycle including an outdoor unit provided with a compressor and a heat exchanger on a side of a heat source, and a plurality of indoor units, the refrigeration cycle comprising a refrigerant circulating in the refrigeration cycle, and being a non-azeotropic refrigerant, and a liquid receiver provided between the heat exchanger on the heat source side and the indoor units, and wherein a refrigerant vapor, in which a low boiling point refrigerant is rich, is taken out from the liquid receiver at low load, and the taken-out refrigerant is condensed and stored, whereby the number of times, in which the compressor is made off, is reduced.